This invention relates in general to gas burners, and more particularly, to burners for gas-fired cooking grills.
Gas-fired cooking grills have become quite popular for outdoor cooking, particularly in residential areas, and to a large measure have replaced the traditional charcoal grill. The typical gas-fired grill has a relatively deep housing that is mounted upon a pedestal. A grate extends over the upper end of the housing for supporting the food that is to be cooked, and usually a lid is hinged to the housing to completely enclose the grate. This enables the grill to be used as an oven and further protects components within the housing during periods of nonuse. One of those components is a burner to which a combustible gas is supplied for producing a flame below the grate. Actually, the burner is part of an assembly that in addition to the actual burner, includes an upright venturi tube that leads into the burner. This tube in the typical grill extends down into the pedestal where it fits over an orifice from which a regulated supply of a gaseous fuel, such as natural gas or propane gas, is discharged. Within the venturi tube the gaseous fuel mixes with air to form a combustible mixture that ignites upon issuing from the apertures in the burner itself.
Initially, the burners for gas grills were made almost exclusively from cast iron. However, iron casting has become quite expensive. Moreover, the intense heat within a grill housing will cause conventional cast iron to corrode, producing a scale that clogs the burner apertures in some places and leaves them too large in others. This of course distorts the flame such that it is considerably more intense in some regions than in others.
These disadvantages led grill manufacturers to substitute stamped burners for cast burners. The typical stamped burner is formed entirely from a metal that will withstand the heat without oxidizing, and usually includes two stamped sections which are joined together so as to create a narrow chamber or plenum between them. One or both of the sections has the burner apertures, and the lower section is connected to a venturi tube that fits down into the pedestal of the burner to the control valve where the tube directs gas from the valve to the burner plenum. To facilitate packaging the burner and the venturi tube are usually supplied as separate components, the tube having at its upper end a flange that is subsequently secured by means of sheet metal screws to the lower section of the burner. Normally, an asbestos gasket is interposed between the flange and the burner. Also in the region where the venturi tube opens into the burner plenum, the burner is provided with separate baffles to more evenly distribute the gas to burner apertures, and thereby prevent an excessive amount of gas from flowing to the apertures closest to the venturi tube. All of this contributes significantly to the cost of manufacturing stamped burners.
Consideration has been given to joining the venturi tube and burner into a single unit, but this presents packaging and inventory problems. As to the former, a burner having a long venturi tube projected from it is certainly more difficult to pack and ship than a burner and a detached venturi tube. As to the latter, one basic burner configuration is often used with a variety of venturi tube configurations to accommodate grills of different size and manufacture. Instead of stocking one type of burner and a variety of venturi tubes, as is possible when the two can be detached from one another, one must instead stock a separate burner assembly for each venturi tub configuration.